Bacterial Vaginal Infections in Pregnancy

Frederick R. Jelovsek MD

Bacterial vaginal infections are a pain in the bottom anytime, but during pregnancy, they can actually cause other serious problems with respect to the outcome of the pregnancy. Bacterial vaginosis is associated with preterm labor, premature rupture of the bag of waters which leads to preterm labor, infection of the amniotic fluid, placenta and baby during labor. In fact it is estimated that 15%-20% of all pregnant women have bacterial vaginosis, BV.

Types Of Vaginal Infections

A recent article, Hammill H: Bacterial vaginal infections in the pregnant patient. The Female Patient, 1999 (Aug);suppl 25-28, looked at the diagnosis and management of BV infections during pregnancy.

Are there different types of bacterial vaginal infections?

There are two main types of bacterial vaginal infections, a general mixed bacteria infection called bacterial vaginosis (BV) and a streptococcal bacterial vaginosis. Either one of them can be associated with complications for a pregnant woman. BV can lead to preterm labor and delivery. Streptococcal vaginitis can do the same and, in addition, it can cause an infection in the newborn baby. This is a very serious infection and about 4% of babies who get this infection die and the ones who survive have other serious infections in the brain, lung and bone.

What is a streptococcal vaginosis?

Vaginosis caused by streptococcus presents as a creamy, white discharge. There is not usually a burning of the vulva as there is with yeast infection and the discharge is not very odorous like a bacterial vaginosis. If the doctor looks at the discharge under a microscope, there are no white blood cells and no lactobacilli, the normal bacteria of the vagina.

There are several streptococcal species that can be present in the vagina, group A, B and D strep. About 70% of strep vaginosis is due to group B and about 30% are due to group D. Group A infections are rare.

Strep vaginosis can occur spontaneously but very often it is caused by the antibiotic treatment given for bacterial vaginosis. Metronidazole (Flagyl®) is the usual treatment for BV but it does not treat strep, therefore an overgrowth of streptococcus frequently occurs. This is such a problem that one vaginal cream, clindamycin vaginal cream, which was frequently used for bacterial vaginosis during pregnancy, is no longer approved because it results in a strep vaginosis. Oral clindamycin is still approved for bacterial vaginosis and there is no evidence that it produces a strep overgrowth.

Should I be routinely tested for bacterial vaginosis during pregnancy?

Any woman who has had a previous streptococcal vaginal infection during pregnancy or even a history of preterm labor or preterm rupture of the membranes during a previous pregnancy should be tested again or even just empirically treated as if she had such an infection. This testing should be both for bacterial vaginosis, by microscopic exam of vaginal secretions or special amine spot tests, and for streptococcal vaginosis by streptococcal bacterial cultures or reliable screening test. The testing or treatment for bacterial vaginosis should take place after 16 weeks pregnancy and the testing or treatment for streptococcal vaginosis should take place at 35-37 weeks or anytime during presentation for labor, suspected labor or with a history of rupture of the bag of waters (membranes) prior to the onset of labor.

For most lower risk women, there are generally two different strategies:

Bacterial vaginosis

Aggressively diagnose and treat any pregnant woman for vaginosis who has symptoms of vaginal discharge, odor or vulvar irritation

Routinely screen after 16 weeks pregnancy for BV, and treat and follow-up those with BV to make sure recurrences are minimized (note that this approach has not yet been excepted as cost effective by many providers but it makes sense if 15-20% of all pregnant women have BV and up to 50% are completely asymptomatic)

Streptococcal vaginosis

Screen all low risk pregnant women for group B streptococcus at 35-37 weeks gestation and those who are positive should be treated for active infection during labor automatically

Screen or treat only high risk patients with a past history of preterm complications or with intrapartum fever of more than 100.4 deg F (38.0 deg C) or membrane rupture more than 18 hours

If bacterial vaginosis causes complications of pregnancy, will it also cause difficulty conceiving or cause miscarriage?

No, it does not seem to cause difficulty getting pregnant. Yes, it is associated with an increased incidence of miscarriage. A recent study, Ralph SG, Rutherford AJ, Wilson JD: Influence of bacterial vaginosis on conception and miscarriage in the first trimester: cohort study.BMJ 1999 Jul 24;319(7204):220-3, showed a miscarriage rate of 31.6% in women with bacterial vaginosis compared with 18.5%, a normal background rate, in women with normal vaginal bacteria.

How To Prevent Infections

Is there anything I can do during pregnancy or before to prevent or detect bacterial vaginosis?

Self-care diagnosis and treatment are just beginning to be introduced into standard medical therapy recommendations. A study in Germany to prevent premature births used a vaginal pH glove that women used to check their vaginal pH twice a week during pregnancy. An elevated pH of over 4.7 (pH is a measure of acidity of the vaginal secretions) was associated with bacterial vaginosis. It was then treated with lactobacillus tablets (normal vaginal bacteria) or antibiotics and the incidence of preterm labor and very low birthweight infants was reduced. The vaginal pH glove is not yet available in the U.S. but it may soon be.

Tablets containing lactobacillus to place in the vagina to restore the normal bacteria flora are available at many pharmacies and health food stores. Doctors would not recommend that you use them routinely unless there is a need for them because routine use of douching has been shown to actually produce more bacterial vaginosis than it cures. Thus the concept of putting any medical substance into the vagina on a routine basis if not really needed is thought to be able to potentially cause alterations that can lead to an infection.

A better strategy might be to work with your doctor to be sure to check vaginal secretions either before conception or after about 16 weeks of pregnancy ( because there is a very low incidence of new occurrence of vaginosis after 16 weeks). The doctor may do a microscopic exam or just check a vaginal pH. If either are positive, discuss antibiotic treatment for this and then consider following up to make sure the infection is gone. If you have trouble with recurrent BV, ask the doctor if you can use the vaginal lactobacillus tablets to try to decrease the chance of recurrence. It also goes without saying that douching is not something you should do during pregnancy and even when not pregnant, you should consider not douching on a routine basis.